Psychrometric control of dust mites in UK housing

Abstract

This note reviews the principles of psychrometric control of dust mites. It is shown that a simple passive equilibrium model explains the functional form of the empirical critical equilibrium humidity curve for Dermatophagoides farinae. The note confirms the inappropriateness of the Korsgaard limit of 7 g kg^-1 as a practical constraint in the UK. The impact on UK housing of maximum RH limits proposed by Cunningham is examined. At temperatures typical of much UK housing, these limits are likely to be exceeded for most of the winter. Acceptable conditions are likely to be achievable only in dwellings with mean internal temperatures in the region of 20°C. Such temperatures are rarely achieved in the UK, except in very well insulated dwellings.